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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 10 (1991), S. 0 
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Vigh-Teichmann I, Petter H, Vigh B. GABA-immunoreactive intrinsic and 4mmunonegative secondary neurons in the cat pineal organ. J Pineal Res 199 1 : 10: 18-29.〈section xml:id="abs1-1"〉〈title type="main"〉Abstract:The pineal organ of the cat was studied by postembedding gamma-aminobutyric acid (GABA) immunocytochemistry. Two polyclonal rabbit GABA antisera were used with light microscopic peroxidase and electron microscopic immunogold techniques. A considerable number of intrinsic neurons are scattered in the proximal portion of the pineal organ. Some of the nerve cells were GABA-immunoreactive; other neurons as well as pinealocytes and glial/ependymal cells were immunonegative. A few GABA-immunoreactive neurons behaved like CSF-contacting neurons by penetrating the ependymal lining of the pineal recess. GABA-immunoreactive neurons were more frequently found in the subependymal region. Small bundles of thin immunoreactive unmyelinated and thick immunoreactive myelinated nerve fibers occurred in the proximal pineal, especially near the habenular commissure. There were synapses of various types between GABA-immunoreactive and -immunonegative fibers. Myelinated immunoreactive axons seemed to loose their sheaths after entering the organ. Axon-like processes of pinealocytes terminated on dendrites of immunonegative neurons present near the posterior and habenular commissures. The axons of these neurons were found to join the commissural fibers and may represent a pinealofugal pathway conducting information originating from pinealocytes. The pinealocytic axons forming ribbon-containing synapses on dendrites of secondary neurons speak in favor of the sensory-cell nature of the pinealocytes. The pinealopetal myelinated GABA-immunoreactive axons and the intrinsic “GABA-ergic” neurons are proposed to inhibit the action of intrapineal neurons on which the pinealocytic axons terminate.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The fine structure and opsin immunocytochemistry of the pineal and parapineal organs of the salmonid fish Salvelinus alpinus, the landlocked Arctic charr, were studied and compared with the retina in various developmental stages, from prehatching to two-month-old. For opsin immunocytochemistry two polyclonal antibovine rhodopsin and the monoclonal antichicken opsin antibodies OS-2 (detecting blue and green pigments) and OS-1 (detecting green and red pigments) were used.Histologically, the pineal organ consists of nervous tissue like that of the retina. It is composed of photoreceptor pinealocytes, which formed axon terminals containing synaptic ribbons, on the dendrites and perikarya of secondary pineal neurons. Already in prehatching embryos, both the pineal and retinal photoreceptors display well-developed outer segments and form synaptic terminals. The distal part of the pineal organ differentiates earlier than its proximal stalk. The differentiation of the retina starts centrally, but the caudal and dorsal retinae are differentiated earlier than the rostral and ventral ones. At the end of the larval period, the lateral retina is still undifferentiated.In all stages studied, (rhod)opsin immunoreactivity was found in the outer segments of the pineal organ and rod-type retinal photoreceptors, a finding speaking in favour of the presence of the opsin of a rhodopsin/porphyropsin. Cone-type retinal photoreceptors identified morphologically in the pre- and posthatching stages were opsinimmunonegative with the four primary antisera used. This result suggests that in the charr the opsins of cone visual pigments differ in their chemical nature from those of rhodopsin/porphyropsin. The parapineal organ was opsin immunonegative. Using the monoclonal antibody OS-2 opsin immunoreactivity was also detected in inner segments, perikarya, and pedicles of rod-type photoreceptors of both retina and pineal organ of embryos and 1- to 4-day-old larvae. This may indicate a high level of opsin gene expression during photoreceptor growth around hatching. The well-developed pineal organ and its opsin content are discussed in connection with the photonegative behaviour of the larval charr.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 21 (1970), S. 322-337 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Verhalten der AChE-Aktivität wurde in der periventrikulären Substanz des Zentralnervensystems von Fischen, Amphibien, Reptilien, Vögeln und Säugern enzymhistochemisch untersucht. In den bisher bekannten Liquorkontakt-Neuronengebieten — es handelt sich um Gebiete mit Nervenzellen, die durch ventrikuläre Portsätze und spezielle Nervenendigungen mit dem Liquor cerebrospinalis in direkter Berührung stehen- und auch in anderen periventrikulären Kerngruppen wurden AChE-positive Liquorkontakt-neurone gefunden. Die meisten derartigen, stark AChE-positiven Nervenzellen wurden im periventrikulären Höhlengrau des Hypothalamus und um den Zentralkanal des Rückenmarks der untersuchten Arten beobachtet. Im Telencephalon und Mesencephalon der Reptilien kamen nur vereinzelte AChE-positive Liquorkontaktneurone vor. Im Hypothalamus enthalten folgende Gebiete AChE-positive Liquorkontaktnervenzellen: Paraventrikularorgan, Recessus praeopticus-Organ, Nucleus praeopticus und paraventricularis, Nucleus infundibularis, Nucleus lateralis tuberis, Nucleus periventricularis hypothalami, Recessus lateralis der Amphibien, Recessus mamillaris der Fische und Saccus vasculosus. Im Rückenmark werden AChE-positive Liquorkontaktneurone um den Canalis centralis in Höhe der Urophyse und aller anderen Segmente des Rückenmarks beschrieben. Die AChE-Aktivität ist nicht nur in den Perikaryen, sondern auch in den ventrikulären Fortsätzen und Liquor-Endigungen der Zellen vorhanden. Die AChE-positiven Zellen der verschiedenen untersuchten Gebiete wurden in Hinsicht auf eine „cholinerge” Komponente des Liquorkontakt-Neuronensystems diskutiert.
    Notes: Summary The distribution of the activity of acetylcholinesterase (AChE) was studied enzyme-histochemically in the periventricular substance of the central nervous system of fishes, amphibians, reptilia, birds and mammals. In the liquor contacting neuronal territories known until now — the areas containing nerve cells which are directly contacting the cerebrospinal fluid by ventricular processes and special nerve terminals — and also in other periventricular nuclei, AChE-positive liquor contacting neurons were found. Most of these strongly AChE-positive nerve cells could be observed in the periventricular gray of the hypothalamus and around the central canal of the spinal cord of the species studied. In the telencephalon and mesencephalon of reptilia, only sporadic, AChE-positive liquor contacting neurons occured. In the hypothalamus, the following territories contained AChE-positive liquor contacting nerve cells: the paraventricular organ, preoptic recess organ, preoptic and paraventricular nuclei, infundibular nucleus, nucleus tuberis lateralis, the periventricular, hypothalamic nucleus, lateral recess of amphibians, mamillar recess of fishes, and the vascular sac. AChE-positive liquor contacting neurons were described around the central canal on the level of the urophysis and in all other segments of the spinal cord. Activity of AChE is not only present in the perikarya of the liquor contacting nerve cells, but also in their ventricular processes and liquor-terminals. The AChE-positive cells of the various territories investigated, were discussed with regard to a “cholinergic” component of the liquor contacting neuronal system.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Vitamin A immunoreactive sites were studied in the retina and pincal organ of the frog,Rana esculenta, by the peroxidase antiperoxidase, avidin-biotinperoxidase and immunogold methods. Indark-adapted material, strong immunoreaction was found in the outer and inner segments of the photoreceptor cells of both retina and pineal organ, as well as in the pigment epithelium, retinal Müller cells and pineal ependymal cells. Inlight-adapted retina, cones and green (blue-sensitive) rods were immunopositive. At the electron microscopic level, immunogold particles were found on the membranes of the photoreceptor outer segments as well as on the membranes of the endoplasmic reticulum and mitochondria. Individual retinal photoreceptor cells exhibited strong immunoreaction in the distal portion of the inner segment, the ciliary connecting piece and the electron-dense material covering the outer segment. In the pigment epithelium, the immunolabeling varied in intensity in the basal and apical cytoplasm and phagocytosed outer segments. The immunocytochemical results indicate that retinoids (retinal, retinol and possibly retinoic acid) are present not only in the photoreceptor cells of the retina but also in those of the pineal organ. The light-dependent differences in the immunoreactivity of vitamin A underlines its essential role in the visual cycle of the photopigments. Our results suggest that the pineal ependyma plays a role comparable to that of the Müller cells and pigment epithelium of the retina with regard to the transport and storage of vitamin A. The presence of a retinoid in nuclei, mitochondria and cytoplasmic membranes suggests an additional role of vitamin A in other metabolic processes.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 91 (1989), S. 161-168 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The surface of the pineal organ of the rat is covered by a leptomeningeal tissue, the continuation of the corresponding meningeal layers of the diencephalon. The pineal leptomeninx consists of stratified arachnoid and of pia mater cells which follow the vessels into the pineal nervous tissue. The pineal arachnoid contains electron-lucent and electron dense cells differing from each other in their cytoplasmic components. Corpora arenacea of various size and density occur among these arachnoid cells and can grow into the pineal organ alongside pia mater tissue. Acervuli often form groups in circumscribed meningeal “calcification foci”. Concrements are absent or rare in the 1- and 2-month-old animal, while they are usually present in the 4- and 6-month-old rats. The electronmicroscopic localization of Ca-ions was studied in 2- and 4-month-old rats by potassium pyroantimonate cytochemistry. In the 4-month-old animals, arachnoid cells containing a varying amount of Ca-pyroantimonate deposits were found first of all around corpora arenacea, but there were also cells free of deposits in the close vicinity of the acervuli. Deposits were preferentially localized to the cytoplasm of electron dense arachnoid cells and to the cell membrane of electron-lucent cells. Most of the precipitates occurred in locally enlarged intercellular spaces. Here, microacervuli were found in 4-month-old animals suggesting that a calcium-rich environment was responsible for the appearance of the concrements. Intermediate stages between the small acervuli and large concentric corpora arenacea may indicate an appositional growth of the acervuli in the calcification foci. Occasionally, acervuli were also located inside meningeal cells. There was no sign of the formation of acervuli in the pinealocytes or elsewhere in the pineal nervous tissue proper, in the age interval (1- to 6-month-old animals) studied. These findings confirm the view that corpora arenacea can be produced in the rat by the pineal leptomeninx. The laboratory rat seems to be usefull in studying pineal calcification of the meningeal type.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 80 (1967), S. 229-245 
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Characteristics of the ependymal cells of the Paraventricular Organ (PVO) in the sparrow are strongly dilated ergastoplasmic cisternae filled with a moderately dense substance, the absence of cilia and a long basal process ending around capillaries. Elongated cells having a pale cytoplasm (“light cells”) are interposed between the ependymal cells. These cells protrude into the ventricle lumen with a bulbous cytoplasmic swelling; centrioles and several dense-core vesicles occur frequently in them. Two types of nerve cells have been identified in the PVO. The more superficial cells — called type-I neurons have a dendrite-like process which, after passing the ependymal layer reach the ventricle surface and end there freely with a bulbous swelling (“club”). The whole neuron contains dense-core vesicles of an average diameter of 840 Å; the extensive Golgi region is located in the dendrite. The larger type-II neurons situated in the deeper layers show a folded nuclear membrane, large mitochondria and rarely dense-core vesicles; the Golgi apparatus is enclosed in the perikaryon. The nerve cells are embedded in a feltwork of glial and neural processes the latters showing often synaptic (axodendritic) junctions. The majority of the synapses are supposed to occur between the axon-like processes of the typeI neuron and dendrites of the type-II neuron. Axo-somatic synapses can be found not infrequently on the perikarya of the latters. The nature of the free ventricular endings of the neurons and the possible function of the PVO are discussed in the text.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 221 (1981), S. 451-463 
    ISSN: 1432-0878
    Keywords: Pineal photoreceptors ; Pinealocytes ; Opsin immunoreactivity ; Rhodopsin-like photopigments ; Comparative aspects (vertebrates)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An antibody to opsin isolated from rod outer segments of the frog retina was applied in light- and electron-microscopic immunocytochemical studies to the pineal organ of various vertebrates (Cyprinus carpio, Carassius auratus, Rana esculenta, Emys orbicularis, Pseudemys scripta elegans, Lacerta agilis and viridis, Gallus domesticus, Columba livia, Melopsittacus undulatus, Serinus canaria, Taeniopyga punctata, Didelphis virginiana, Erinaceus roumanicus, Myotis myotis, rabbit, rat, cat). A strong immunoreaction was visible in the outer segments of the pinealocytes of one anuran and several teleost species. The outer segments of pinealocytes in the chelonian reptiles and birds also contained immunoreactive opsin. Ultrastructurally, PAP complexes were localized to the photoreceptor membranes of the outer segments. Immunoreactivity for opsin could not be demonstrated in the lacertilian parietal eye and pineal organ. In the opossum (Marsupialia), pinealocytes remain in contact with the intrapineal invaginations of the pineal recess. In insectivores, the cilia of the pinealocytes exhibit a relation to glial cells similar to that between the outer segments of retinal photoreceptors and the pigment cells. The cilia of mammalian pinealocytes did not show a clear-cut immunoreactivity to opsin with the electron-microscopic technique employed.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0878
    Keywords: CSF-contacting neurons Spinal cord ; Terminal ventricle ; Neurosecretory axon terminals ; Vertebrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cerebrospinal fluid (CSF)-contacting neurons were studied by means of electron microscopy in the spinal cord and/or terminal ventricle of the ray, Raja clavata (Elasmobranchii), the opossum, Didelphis virginiana (Marsupialia), the mouse, Mus musculus, and the guinea pig, Cavia cobaya (Rodentia). Dendrites of the CSF-contacting neurons in the spinal cord of the ray penetrate the ependyma of the central canal and form terminals bearing stereocilia. Axons apparently belonging to these neuronal perikarya terminate on the basal lamina of the spinal cord near the fila of the radix ventralis. In the opossum, a representative of metatherian mammals, the dendritic terminals of the CSF-contacting neurons resemble those of the phylogenetically ancient lower vertebrates and are endowed with many stereocilia. In such eutherian mammals as the mouse and the guinea pig, the corresponding stereocilia are usually less developed. There are numerous CSF-contacting neurons in the wall of the terminal ventricle of the mouse. Since the dendritic terminals of the spinal CSF-contacting neurons resemble those of known sensory cells and the axon terminals on the basal lamina resemble ultrastructurally neurosecretory endings, we suppose that the former are receptive to stimuli exerted by the internal (ventricular) CSF and capable of translating them into a neurosecretory output directed toward the external (subarachnoid) CSF. With their periradicular terminations the axons of the CSF-contacting neurons establish an extended, special site for neurosecretory release along the ventrolateral sulcus of the ray spinal cord.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0878
    Keywords: Pineal organ ; Photoreceptors ; Cones and rods ; Oil (lipid) droplets ; Rhodopsin ; Rana esculenta (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pineal organ of the frog, Rana esculenta, was studied by use of light- and electron-microscopic methods including immunoreaction against opsin. Most of the morphologically classified cone-type outer segments of the pineal photoreceptors reacted with antisera against opsin of the bovine retina that is dominated by rods. Some of the outer segments of pineal photoreceptor cells remained unstained in accord with the reference tissue, the frog retina, where generally the rods were opsin-positive and most of the cones opsin-negative. The opsin-negative outer segments of pineal photoreceptors were found in continuity with inner segments each containing a large oil (lipid) droplet. These oil droplets stained intensely with osmic acid, Sudan III, Sudan Black B or Scharlach R in cryostat sections, and were soluble in lipid solvents. In ultrathin sections of osmicated material, the oil droplets were homogeneous and of varying electron density. Approximately one tenth of the pineal photoreceptors contained oil droplets and at the same time possessed opsin-immunonegative outer segments. Since in the retina oil droplets and a negative immunoreaction against bovine opsin are characteristic of cones, we suggest that in the pineal organ they also mark “conetype” photoreceptors scattered among “rod-type” photo-receptors, the latter displaying a positive immunoreaction with the antisera used.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 183 (1977), S. 541-552 
    ISSN: 1432-0878
    Keywords: Cerebrospinal fluid contacting neurons ; Spinal cord ; Dendrites ; Receptor endings ; Neurosecretory axon terminals ; Various vertebrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cerebrospinal fluid (CSF) contacting neurons have a dendritic process which protrudes into the central canal, and is provided with one long kinocilium and many shorter stereocilia (about 80 in the turtle) as revealed by scanning electron microscopy. The shape, number and arrangement of the cilia are similar to those of known receptor endings. The silver impregnated axons of these cells converge to a paired centrosuperficial tract forming terminal enlargements at the ventrolateral surface of the spinal cord. Lying among glial endfeet these terminals are ultrastructurally similar to those present in known neurosecretory areas. The nerve endings are attached to the basal lamina, and they comprise many synaptic vesicles (200 to 400 Å in diameter), as well as granular vesicles of different sizes (diameter 600 to 1800 Å). The axons may lie within finger-like protrusions on the surface of the spinal cord, or they may terminate around vessels. Morphological evidence suggests that these nerve terminals and the corresponding CSF contacting perikarya represent a spinal neurosecretory system possibly influenced by information taken up by its special dendrites protruding into the inner CSF space.
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